Service Details

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Mailer shield service – closing November 2018

Following the annual review of the mailer shield service, we consider this service to be no longer capable of scaling to adequately protect the size of email services that are implemented in the current environment.

Therefore, the decision has been made to withdraw the service from 30th November 2018 and we will no longer be accepting new applications.

We will be contacting existing users to offer transition advice and guidance before it closes and will continue to support our existing mailer shield service customers until the service is withdrawn.

Service Details

  • Contacts
  • Technical details
  • Conditions of use
  • Legal considerations
  • Service implementation
  • Service levels



Janet or its contractors may need to contact your organisation for various purposes such as:

  • routine announcements about the operation of the service or your use of it
  • notices about abnormal operation or about the behaviour of your own mail system (e.g. failure to accept mail for a significant period)
  • requests that you take some urgent action in an emergency, either in the configuration of your e-mail system or in respect of the activity of one of your users
  • policy questions about your continued use of the service or escalation of unresolved requests.

The registration process includes contact points and methods to cover these needs. The Janet Service Desk will write to one of the contact addresses from time to time to confirm that the details Janet holds are still accurate.

It is a condition of your use of the service that you respond in a timely manner to requests sent to the contact addresses you provide.

You must maintain a ‘postmaster’ address for all your domains which send or receive e-mail, and you must arrange for the postmaster address to be an alias for a site service contact, such as a helpdesk or the individual responsible for the mail service. E-mail sent to has to be read and acted upon in a timely manner. In addition to support for the postmaster e-mail address, Janet requires a name and telephone contact number of an individual.

Contact e-mail addresses will be included in a mailing list that the service managers may use for announcements. This mailing list will not be available to anyone except the managers.

Technical details

Janet needs to know about the domain or domains which form part of your addresses. You will probably specify your usual main domain name, any alternative domain names which you use for historical or other reasons, and possibly a few subdomains. For example:

You can, if you wish, specify instead and all subdomains

but this places additional responsibilities on you, and the service managers will discuss it with you before accepting your registration request.

Janet also needs some details of the e-mail systems within your organisation. The registration template asks for certain basic information. The service managers will write to the operational contacts you provide, to agree a time when necessary changes will be made. In many cases they will also need further technical information before they are able to configure the service for you.

There are a number of things which need to be correctly set up which are not in Janet’s direct control and where you or your contractors or consultants will need to take some action. These are detailed in Setting up Janet Mailer Shield, under:

  • Inbound relay
  • Outbound relay

Conditions of use 
The Janet Mailer Shield is not a managed e-mail service. Organisations remain responsible for the operation of their own mail server or servers to provide local delivery and user management, for security, and for conforming to:

Use of the Janet Mailer Shield service is subject to these policies and the additional notices below. You are also expected to comply with Internet RFCs (Request for Comments) as they apply to e-mail: see References.

Note that the purpose of the service is to reduce the likelihood that you will inconvenience or be inconvenienced by other Internet users through certain kinds of abuse. You are still required to maintain and operate your own equipment and processes for the same purpose.

Specifically, you MUST ensure that no computer in your network is open to any connection (mail, web form or other proxy) which could result in unauthorised people passing mail to anywhere outside your own network. This can normally be achieved by carefully configuring your router or firewall, disabling services not specifically needed on each computer, active management of mail servers and directions to your users. All these are routine good practice in any network.

Legal considerations

Using the Janet Mailer Shield service raises issues of privacy, data protection and access by law enforcement agencies. Organisations applying to use the service must indemnify Janetits agents and subcontractors against any and all liability for claims arising out of their use of the service.

All users of your e-mail facilities must be made aware that their messages are being processed by Janet during the provision of this service. When you apply to use the service, Janet asks you to explain how you are going to communicate this to them. The following text may be useful as a basis for your internal notice:

This Organisation’s e-mail may be passed through a Janet computer not under the management of this Organisation. We are satisfied that Janet has no interest in the individual sending or receiving any message or the contents of the message, and will under normal circumstances destroy any records of the passage of the message no more than two days after the message is delivered.

If you are concerned about the impact of this arrangement on your privacy, please speak to a named responsible personThe Organisation’s internal arrangements for privacy and related matters are available for your inspection at some suitable place.”

The Janet systems providing the service make a log record of each message. Janet and its contractors use this information without identifying individual messages to confirm that the volume of traffic Janet is handling for you is within the limits set down for the service, to report the volume of your traffic to you and to JISC (Joint Information Systems Committee) or their agents, to review the future resource needs of the service, and for no other purpose.

However, you should consider what records of your own you need to keep. In the case of misuse of the service by your user, you are expected to identify any individuals responsible and to take action agreed with Janet.

Service implementation

The Janet Mailer Shield service consists of several relays, located in the core of Janet. They are securely maintained and operated. Janet will tell you which relay or relays to use at the time your application to use the service is accepted.

In configuring your network and your mail server to use the Janet relays, you should arrange to accept connections from all the IP addresses for each relay assigned to you. There is no guarantee that your mail will come from the same IP address all the time.

If at any time you need to send mail out through the assigned relay and the service manager agrees to such use, you will need to configure your mail server to use the IP address for one particular relay. It is advisable to have a record of all the relay IP addresses readily available, with work instructions for making the necessary configuration change to one of them.

Your users should be made aware that under current UK legislation Janet, like any other network provider, may be obliged to capture, preserve and reveal to the proper agencies details of some or all of the individual messages which the service handles for you, including personal data and message contents. Janet may then be forbidden to tell your organisation that this is the case even in response to a direct question. Naturally, when Janet is able to answer such a question, it will do so. Janet can accept no liability for any civil or criminal liability that may be incurred by end‑users as a result of the operation of Janet Mailer Shield.

The loss of a message by the Janet relays is very hard to establish, but reports of loss will be promptly investigated so far as is practicable. However, Janet can accept no liability for any damage or loss resulting directly or indirectly from any failure of the service.

References lists some of the relevant UK legislation.

Service levels



Performance targets


The Janet relays are running, accessible from Janet and the Internet, and configured to relay messages for you as agreed.

99.5% of the time measured over any period of 30 consecutive days.

Message delay

The time between a message being transferred to a service relay and the first attempt to transfer it to your mail server.

No more than 10 minutes for 99.9% of messages transferred.

Message loss

Loss of a message without trace, or rejection by the Janet relays of a message with an address in one of your domains.

The loss of a message by the Janet relays is very. Reports of loss will be promptly investigated so far as is practicable.

Message damage

Alteration of the message contents or of parts of the message header intended for the recipient.

The normal handling of e-mail by the service is in accordance with current standards RFC 2821 and RFC 2822. Message contents should never be altered. Reports of alteration will be promptly investigated so far as is practicable.

Change requests

Janet will seek to make any changes you request to the configuration of your service within four working days, with the same reservations as those for the processing of applications to use the service.

Misdirected messages

Messages presented to your mail server which are not for the domains you register with the service, or messages which are for your domains which the service routes elsewhere.

Reports of such events will be promptly investigated so far as is practicable.

Unwanted messages

Unsolicited Bulk E-mail, messages for invalid addresses in your domains, messages carrying viruses, worms or other potentially damaging programs, or messages with potentially offensive or illegal contents.

The service relays do not filter messages. Janet takes no responsibility for any aspect of the message contents but will give you all practicable assistance in identifying the origin of messages causing concern.